Dundee United manager Jim Goodwin "firmly" believes Kilmarnock's winning goal should not have stood after his side lost 1-0 at Rugby Park.
Marley Watkins' controversial header gave Kilmarnock victory and moved Derek McInnes' side to within three points of the Scottish Premiership's top six.
United players appealed for a foul after Watkins collided heavily with goalkeeper Jack Walton as they challenged for a high ball in the six-yard box on 72 minutes, but the goal stood following a VAR review.
Goodwin's visitors were further incensed at the death when they were denied a penalty after the ball hit Corrie Ndaba's hand from a cross.
"The major disappointment for us is the goal that we concede," Goodwin told BBC Scotland.
"VAR is there to help in those situations. The centre-forward for Kilmarnock has his arm right across Jack Walton's face, making it impossible for Jack to get off the ground to try and catch the ball. I firmly believe that that goal should've been ruled out."
Kilmarnock boss Derek McInnes commented: "It's a mistake, maybe, from the goalkeeper. Marley uses his experience and just becomes a nuisance and gets the goal."
In a game of few openings, United debutant Allan Campbell and the hosts' Joe Wright had the best sights of goal in the first half.
Then Premiership top scorer Sam Dalby drew a fine save from Kilmarnock's Kieran O'Hara in the second, before United's Ryan Strain headed over.
Kilmarnock climb two places to ninth, while third-placed United remain two points above Aberdeen.